At western edge of Aquatic Park, New York performance artist Sarah Cameron Sunde stands in the Bay on Friday Aug. 15, 2014 in San Francisco, Calif. Her intent is to stay for a full cycle of tides, a more-than 13-hour process. The project is called "36.5: A Durational Performance with the Sea," and is meant to raise awareness about rising sea levels. She has done this in other two other times in Bass Harbor, Maine and Akumal, Mexico.

Photo: Mike Kepka

At western edge of Aquatic Park, New York performance artist Sarah...

Image 2 of 9

At western edge of Aquatic Park, New York performance artist Sandra Cameron Sunde stands in the Bay on Fridday Aug. 15, 2014 in San Francisco, Calif. Her intent is to stay for a full cycle of tides, a more-than 13-hour process. The project is called "36.5: A Durational Performance with the Sea," and is meant to raise awareness about rising sea levels. She has done this in other two other times in Bass Harbor, Maine and Akumal, Mexico.

Photo: Mike Kepka

At western edge of Aquatic Park, New York performance artist Sandra...

Image 3 of 9

At western edge of Aquatic Park, New York performance artist Sandra Cameron Sunde stands in the Bay on Fridday Aug. 15, 2014 in San Francisco, Calif. Her intent is to stay for a full cycle of tides, a more-than 13-hour process. The project is called "36.5: A Durational Performance with the Sea," and is meant to raise awareness about rising sea levels. She has done this in other two other times in Bass Harbor, Maine and Akumal, Mexico.

Photo: Mike Kepka

At western edge of Aquatic Park, New York performance artist Sandra...

Image 4 of 9

Douglas Dowers and Sasha Petrenko mark each hours New York performance artist Sandra Cameron Sunde stands in the Bay on Friday Aug. 15, 2014 in San Francisco, Calif. Sunde's intent is to stay for a full cycle of tides, a more-than 13-hour process. The project is called "36.5: A Durational Performance with the Sea," and is meant to raise awareness about rising sea levels. She has done this in other two other times in Bass Harbor, Maine and Akumal, Mexico.

Photo: Mike Kepka

Douglas Dowers and Sasha Petrenko mark each hours New York...

Image 5 of 9

At western edge of Aquatic Park, New York performance artist Sandra Cameron Sunde stands in the Bay on Fridday Aug. 15, 2014 in San Francisco, Calif. Her intent is to stay for a full cycle of tides, a more-than 13-hour process. The project is called "36.5: A Durational Performance with the Sea," and is meant to raise awareness about rising sea levels. She has done this in other two other times in Bass Harbor, Maine and Akumal, Mexico.

Photo: Mike Kepka

At western edge of Aquatic Park, New York performance artist Sandra...

Image 6 of 9

At western edge of Aquatic Park, New York performance artist Sandra Cameron Sunde stands in the Bay on Fridday Aug. 15, 2014 in San Francisco, Calif. Her intent is to stay for a full cycle of tides, a more-than 13-hour process. The project is called "36.5: A Durational Performance with the Sea," and is meant to raise awareness about rising sea levels. She has done this in other two other times in Bass Harbor, Maine and Akumal, Mexico.

Photo: Mike Kepka

At western edge of Aquatic Park, New York performance artist Sandra...

Image 7 of 9

Douglas Dowers and Sasha Petrenko mark each hour that New York performance artist Sarah Cameron Sunde (right) stands in the bay.

Photo: Mike Kepka

Douglas Dowers and Sasha Petrenko mark each hour that New York...

Image 8 of 9

At western edge of Aquatic Park, New York performance artist Sarah Cameron Sunde stands in the Bay on Fridday Aug. 15, 2014 in San Francisco, Calif. Her intent is to stay for a full cycle of tides, a more-than 13-hour process. The project is called "36.5: A Durational Performance with the Sea," and is meant to raise awareness about rising sea levels. She has done this in other two other times in Bass Harbor, Maine and Akumal, Mexico.

At 9:26 Friday morning, Sarah Cameron Sunde walked into San Francisco Bay with no plans to come back in until the tide had gone from low to high and back to low again, 13 hours and five minutes later.

"I'm walking out - I hope I survive" were her final words, spoken through a mouthful of pasta as she stepped off the seawall at Aquatic Park. From there she picked her way out 30 feet to a flat rock, which would afford her a few extra inches before the water lapped at her feet.

"I will stand there for the full tidal cycle and let the water rise up to my neck," promised Sunde, who wore street clothes, a wool cap and rubber boots over a wet suit, none of which would keep her warm in the business she was here to attend to, which was to stand perfectly still and silent. Her intent was to draw attention to the threat of rising sea levels from global warning.

But she vowed not to utter a single word of that - or anything else.

Those were the boundaries of "36.5: A Durational Performance With the Sea," which may have been the most dramatic prank since pirates buried Blackbeard up to his neck in sand and waited for the tide to come in and drown him. Or when the Maldivian president and his Cabinet donned scuba gear and conducted business at an underwater desk in 2009 to raise awareness of climate change.

"My goal is to offer a contemplative space for people and to actually put myself in that contemplative space, which is a struggle," said Sunde, 37, a New York performance artist and director who grew up in Palo Alto and graduated from Paly in 1995. "I'm a Palo Alto Viking," she said of the school mascot, "but I can't stand cold water, so I don't know how much of a Viking I really am."

She picked a good day to find out because the water temperature was in the low 60s, and the air felt the same in the morning fog. Hypothermia was a concern, even in a wet suit, so support staff went out to check on her every two hours. Not eating is part of the silence, but water was delivered to keep her hydrated.

"I pee in the wetsuit" to keep it warm, she says, just the way surfers do.

Rising seas

By 2:45 p.m., the water was at chest level and climbing. She wore Neoprene gloves to protect her hands, which were both underwater. One held onto a rope fastened to a rock for balance. Near 4:30, the bay reached high tide of 5 feet, which was within her comfort zone because she stands 5 feet 4. Even if her calculations had been off, the wet suit would have lifted her like a buoy - and also served the political point of her performance.

"The seas are rising, that's inevitable," she said beforehand. "It means that life will change and we'll have to adapt. The question is how much and how fast?"

The numerical reference in "36.5: A Durational Performance With the Sea" refers to her age when she started the project one year ago, while she was on an artist residency in coastal Maine. Deep into thought about art and suffering, she decided to create a performance about it, first on the East Coast.

Sunde normally directs other performance artists, but realizing she would have trouble finding an artist to direct into the water,, she went into the Atlantic herself, standing for 12 hours and 48 minutes in 59-degree water. Her teeth were chattering, but time passed faster than she expected.

"The experience was pretty profound for me," she said. "As I was out there, I realized that it was the beginning of a series, about survival." So on her 37th birthday, Feb. 15, she did it again, this time choosing the 70-degree waters of the Gulf of Mexico, at Akumal. It now happens every six months.

Little participation

Friday's performance was the first time that Sunde invited people to come into the water with her. "Will you stand with me?" was the plea on her website, but as a participatory sport it had limited appeal. Among hundreds of passersby, two women and one man spontaneously waded into waist-high water. Another man came prepared in business suit over wet suit and waded in that way.

"Very San Francisco," said Jennifer Herman, who happened by and was inspired to sit down and write some prose. As performance art she rated it as "not really doing too much," but she thought it might get better later, as the water rose. "It's definitely a cool thing."